TW201923391A - Optical laminate, polarizer and display apparatus which is excellent in durability, suppressed in unevenness, high in visibility, and can be thinned - Google Patents

Abstract

The present invention provides an optical laminate which is excellent in durability, suppressed in occurrence of iridescence, high in visibility, and can be thinned, and a polarizer and a display apparatus using the same. An optical laminate 1 is provided with a primer layer 3 and an antiglare layer 4 having a concave-convex shape on at least one surface in this order on at least one surface of a transparent substrate 2. The transparent substrate 2 contains polyethylene terephthalate having an in-plane retardation of 600 nm or less, and a retardation in the thickness direction of 3000 nm or more.

Description

 Optical laminate, polarizing plate and display device  

The present invention relates to an optical laminate which is suitable for an anti-glare film, and a polarizing plate and a display device using the same.

An optical layered body such as an optical laminate, an antireflection film, or an antiglare film is used for a display member such as a liquid crystal display panel or a touch panel. As a transparent substrate constituting the optical layered body, a cellulose ester film such as cellulose triacetate having excellent transparency and optical isotropic properties has been used, but the cellulose ester film has durability, particularly moisture resistance. The disadvantage of insufficient heat resistance. Therefore, various reviews have been made on the use of a polyethylene terephthalate (PET) film in place of a cellulose ester film as a transparent substrate. The PET film has the advantages of transparency, moisture resistance, heat resistance, mechanical strength, and low cost.

However, since polyethylene terephthalate has an aromatic ring in its molecular structure, birefringence is generated in the surface of the PET film, and an optical laminate using a PET film as a transparent substrate is superposed on the polarizing film. On the other hand, there is a color unevenness such as a rainbow (hereinafter referred to as "rainbow").

As a technique for solving the rainbow spot generated when PET is used for a transparent substrate, for example, it is described in Japanese Patent No. 5,556,926. In Japanese Patent No. 5556926, a rainbow substrate used in a display device is improved by using a polyester substrate having an in-plane retardation (Re) of 3000 nm or more.

With the reduction in thickness and weight of the display device in recent years, the thickness of the optical laminate is required to be reduced, and the thickness of the transparent substrate used in the optical laminate is reduced. However, in order to suppress the rainbow spot generated in the case of using a PET film, as described in Japanese Patent No. 5,556,926, the thickness of the PET film is inevitably increased as the amount of in-plane retardation of the PET film is increased. That is, in the case where a high-delay amount PET film is used for a transparent substrate, it becomes difficult to reduce the thickness.

Accordingly, an object of the present invention is to provide an optical layered body and a polarizing plate and a display device using the same, which are excellent in durability, are suppressed in rainbow spots, have high visibility, and can be made thinner.

The optical layered body of the present invention is provided with a primer layer on at least one side of a transparent substrate comprising polyethylene terephthalate having an in-plane retardation of 600 nm or less and a retardation amount in the thickness direction of 3000 nm or more. And an anti-glare layer having a concave-convex shape on the surface.

Further, the polarizing plate of the present invention is characterized in that a polarizing substrate is laminated on a transparent substrate constituting the optical layered body.

Moreover, the display device of the present invention is characterized by comprising the above optical layered body.

According to the present invention, it is possible to provide an optical layered body and a polarizing plate and a display device using the same, which are excellent in durability, and the rainbow spots and interference fringes are suppressed, the visibility is high, and the thickness can be reduced.

These and other objects, features, aspects and advantages of the present invention will become apparent from the accompanying drawings.

1‧‧‧Optical laminate

2‧‧‧Transparent substrate

3‧‧‧Undercoat

4‧‧‧Anti-glare layer

6‧‧‧ functional layer

Fig. 1 is a cross-sectional view schematically showing an example of an optical layered body of an embodiment.

Fig. 2 is a cross-sectional view schematically showing another example of the optical layered body of the embodiment.

Fig. 1 is a schematic cross-sectional view showing an optical layered body of an embodiment.

The optical layered body 1 is formed by sequentially laminating the undercoat layer 3 and the antiglare layer 4 on one surface of the transparent substrate 2.

(transparent substrate)

The transparent substrate 2 is a film which is a base of the optical layered body 1. The thickness of the transparent substrate 2 is preferably from 12 to 40 μm. When the thickness of the transparent substrate 2 is less than 12 μm, the transparent substrate 2 becomes too thin, and the hardness of the antiglare layer 4 and the strength of the optical layered body 1 are lowered. On the other hand, when the thickness of the transparent substrate 2 exceeds 40 μm, the optical layered body 1 becomes thick, and thus the thickness of the display member using the optical layered body 1 is not reduced.

As the transparent substrate 2, a polyethylene terephthalate film (PET film) having an in-plane retardation (Re) of 600 nm or less and a thickness direction retardation (Rth) of 3000 nm or more was used. By using the PET film in which the in-plane retardation amount and the retardation amount in the thickness direction are within this range, it is possible to suppress the rainbow when the optical layered body 1 is superposed on the polarizing plate or the polarizing mirror is provided on the optical layered body 1. The plaque is formed, and the thin film of the transparent substrate 2 can be realized. When the in-plane retardation amount exceeds 600 nm, the thickness of the transparent substrate 2 is thicker than the above-described 40 μm, which is not preferable. In addition, when the amount of retardation in the thickness direction is less than 3000 nm, the hardness of the antiglare layer 4 constituting the optical layered body 1 is lowered, which is not preferable. The upper limit of the retardation amount in the thickness direction of the transparent substrate 2 is not particularly limited, but is preferably 8000 nm or less.

Further, since the PET film is excellent in low moisture permeability (water vapor barrier property), transparency, heat resistance, and mechanical strength, the durability of the optical layered body 1 can be improved by being used as the transparent substrate 2. In addition, PET films are inexpensive and therefore advantageous in terms of manufacturing cost. The polyvinyl alcohol (PVA) film used in the polarizing plate has high hygroscopicity, expands due to absorption of moisture, and changes in size. Therefore, the protective film is generally bonded to both surfaces in order to protect it from moisture. Since the optical layered body 1 of the present embodiment uses a PET film having water vapor barrier properties (low moisture permeability) as the transparent substrate 2, it is particularly suitable as a protective film for a polarizing plate.

Further, in order to improve the adhesion to the undercoat layer 3 and the antiglare layer 4, the transparent substrate 2 may be subjected to surface modification treatment. Examples of the surface modification treatment include alkali treatment, corona treatment, plasma treatment, sputtering treatment, application of a surfactant, a decane coupling agent, and the like, and Si vapor deposition.

(primer coating)

The undercoat layer 3 has a function as an easy-adhesion layer for improving the adhesion of the antiglare layer 4 to the transparent substrate 2. The undercoat layer 3 is formed, for example, by applying a composition for forming an undercoat layer containing at least an active energy ray-curable resin to the surface of the transparent substrate 2 and curing it. The thickness of the undercoat layer 3 is preferably set to 40 to 120 nm.

(anti-glare layer)

The anti-glare layer 4 has a fine uneven shape on its surface, and mainly provides an anti-glare layer to the optical layered body 1. The anti-glare layer 4 can be formed on the surface of the undercoat layer 3 by, for example, curing the composition for forming an anti-glare layer containing an active energy ray-curable resin and fine particles. The thickness of the anti-glare layer 4 is preferably from 1 to 20 μm. If the thickness of the anti-glare layer 4 is less than 1 μm, the hardness of the anti-glare layer 4 is insufficient. On the other hand, when the thickness of the antiglare layer 4 is more than 20 μm, the thickness of the optical layered body 1 is increased, so that the thickness of the display member using the optical layered body 1 is not reduced.

The active energy ray-curable resin used for the undercoat layer 3 and the antiglare layer 4 is a resin which is polymerized and cured by irradiation with active energy rays such as ionizing radiation or ultraviolet rays. For example, monofunctional, bifunctional or trisole can be used. A functional (meth) acrylate monomer. In addition, in the present specification, "(meth) acrylate" is a generic term for both acrylate and methacrylate, and "(meth) propylene fluorenyl" is both an acryl fluorenyl group and a methacryl fluorenyl group. General name.

The resin material which is cured by irradiation with ionizing radiation can be used singly or in combination: a radical polymerizable functional group having an acrylonitrile group, a methacryl fluorenyl group, an acryloxy group, a methacryloxy group, or the like, A monomer, an oligomer, or a prepolymer of a cationically polymerizable functional group such as an epoxy group, a vinyl ether group or an oxetanyl group. As the monomer, methyl acrylate, methyl methacrylate, methoxypolyvinyl methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, ethylene glycol dimethacrylate can be exemplified. Ester, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, and the like. Examples of the oligomer and the prepolymer include polyester acrylate, polyurethane acrylate, polyfunctional urethane acrylate, epoxy acrylate, polyether acrylate, and alkyd acrylate. Acrylate compound such as melamine acrylate or fluorenone acrylate, unsaturated polyester, tetramethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, bisphenol A An epoxy compound such as glycidyl ether or various alicyclic epoxy compounds, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis{[(3-ethyl-3-oxo) An oxetane compound such as heterocyclobutyl)methoxy]methyl}benzene or bis[1-ethyl(3-oxetanyl)methyl ether.

The above resin material can be cured by irradiation with ultraviolet rays on the condition that the photopolymerization initiator is added. As a photopolymerization initiator, it can be used singly or in combination: acetophenone type, benzophenone type, oxygen sulfur A cationic polymerization initiator such as a radical polymerization initiator such as benzoin or benzoin methyl ether, an aromatic diazonium salt, an aromatic onium salt, an aromatic onium salt or a metallocene compound.

The fine particles contained in the anti-glare layer 4 are various substances which are added to form a fine uneven structure on the surface to exhibit anti-glare properties, and various inorganic fine particles and organic fine particles (fillers) can be used. However, the fine particles are not essential, and if fine irregularities required to exhibit anti-glare properties can be formed on the surface of the anti-glare layer 4, the fine particles can be omitted.

When inorganic fine particles are used as the fine particles added to the antiglare layer 4, inorganic nanoparticles having an average particle diameter of 10 to 200 nm are preferable. The amount of the inorganic fine particles added is preferably from 0.1 to 5.0%.

As the inorganic fine particles, for example, a swelling clay can be used. The swellable clay may have a cation exchange ability, and may be a natural substance or a composite (including a substitute or a derivative) when the solvent is introduced into the layer of the swellable clay to swell. In addition, it may also be a mixture of natural materials and synthetics. Examples of the swellable clay include mica, synthetic mica, vermiculite, Montestone, ironmont stone, beide stone, saponite, hectorite, strontite, nontronite, and sodium hydroxy sulphate. Stone, ilelite, sapite, layered titanic acid, bentonite, synthetic bentonite, etc. These swellable clays may be used alone or in combination of plural kinds. Further, colloidal cerium oxide, aluminum oxide, or zinc oxide may be used alone or in combination as the inorganic fine particles. In addition to the above-mentioned swellable clay, one or more of colloidal cerium oxide, aluminum oxide, and zinc oxide may be used in combination.

As the inorganic fine particles, a layered organic clay is more preferable. In the present invention, the layered organic clay refers to a substance which introduces organic cerium ions into the layers of the swellable clay. The organic cerium ion is not limited as long as it can be organically oxidized by the cation exchange property of the swellable clay. As the inorganic fine particles, for example, synthetic bentonite (layered organic clay mineral) can be used. The synthetic bentonite functions as a tackifier which increases the viscosity of the composition for forming an antiglare layer. The addition of the synthetic bentonite as a tackifier suppresses the precipitation of the resin particles and the inorganic fine particles, and contributes to the formation of the uneven structure on the surface of the antiglare layer.

When organic fine particles (fillers) are used as the fine particles added to the antiglare layer 4, acrylic resin, polystyrene resin, styrene-(meth)acrylate copolymer, polyethylene resin, epoxy resin can be used. Resin particles of a translucent resin material such as an anthrone resin, a polyvinylidene fluoride or a polyvinyl fluoride resin. In order to adjust the refractive index and the dispersion of the resin particles, two or more kinds of resin particles having different materials (refractive index) may be mixed and used. The resin particles (filler) are aggregated in the base resin (adhesive resin) to form a fine uneven structure on the surface of the antiglare layer. In addition, it is possible to impart a concave-convex structure required for exhibiting anti-glare property by forming a random agglutination structure in the anti-glare layer without blending the resin particles. However, by making the anti-glare layer contain resin particles, it is easy to adjust the anti-glare. The size and number of the uneven shape on the surface of the layer.

Further, a suitable composition may be added to the composition for forming an undercoat layer or the composition for forming an antiglare layer. Examples of the solvent include dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, and 1,4-diene. Alkane, 1,3-dioxocyclopentane, 1,3,5-three , ethers such as tetrahydrofuran, anisole, phenethyl ether, polyethylene glycol methyl ether; or acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, methyl Ketones such as butyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; or ethyl formate, propyl formate, n-amyl formate, methyl acetate, ethyl acetate, methyl propionate, Ethyl propionate, n-amyl acetate, and esters such as γ-butyrolactone; in addition, 赛路苏, methyl 赛路苏, 赛路苏, butyl 赛路苏, 赛路苏 acetate class. They may be used alone or in combination of two or more.

Further, in the composition for forming an undercoat layer or the composition for forming an antiglare layer, an antifouling agent, a surface conditioner, a leveling agent, a refractive index adjuster, a photosensitizer, or the like may be added as needed. An additive such as a conductive material.

The optical layered body 1 of the present embodiment can be formed by applying a coating liquid for forming the composition for forming an undercoat layer by a wet coating method on at least one surface of a transparent substrate 2 by a roll-to-roll method. After applying the active energy ray such as an electron beam or an ultraviolet ray to the coating film to cure the active energy ray-curable resin, the coating for forming the anti-glare layer described above is applied to the undercoat layer 3 by a wet coating method. In the liquid, the active energy ray such as an electron beam or an ultraviolet ray is applied to the coating film to cure the active energy ray-curable resin. As the wet coating method, a flow coating method, a spray coating method, a roll coating method, a gravure roll coating method, an air doctor coating method, a knife coating method, a wire coating method, and a knife coating method can be employed. A known method such as a method, a reverse coating method, a transfer roll coating method, a micro gravure coating method, an anastomosis coating method, a casting coating method, a slit nozzle coating method, a calender coating method, or a die coating method. Further, when the coating film is cured by irradiation with ultraviolet rays, a high-pressure mercury lamp, a halogen lamp, a xenon lamp, a fusion lamp or the like can be used when ultraviolet rays are irradiated. The amount of ultraviolet irradiation is usually about 100 to 800 mJ/cm ² .

In the optical layered body 1 of the present embodiment, since the PET film is used as the transparent substrate 2, the cellulose acetate-based film such as cellulose triacetate has a low moisture permeability and excellent water vapor barrier properties. Further, since the PET film is excellent in heat resistance and mechanical strength, the durability of the optical layered body 1 can be improved by using it as the transparent substrate 2. Further, since the PET film is high in transparency and inexpensive, it is suitable as an optical layered body used for an image display device or the like.

In general, when an optical layered body using a PET film as the transparent substrate 2 is used for an image display device, a rainbow spot which is caused by the birefringence of the PET itself is likely to occur. This rainbow spot becomes a factor that reduces the visibility of the image display device. However, in the optical layered body 1 of the present embodiment, by using a PET film having an in-plane retardation of 600 nm or less and a thickness direction retardation of 3000 nm or more as the transparent substrate 2, generation of rainbow spots can be suppressed. It is possible to suppress interference fringes due to the difference in refractive index from the surface treatment layer 4.

(Other variants)

In the optical layered body 1 of the above-described embodiment, at least one layer of the refractive index adjusting layer, the antistatic layer, and the other functional layer 6 such as the antifouling layer can be provided on the antiglare layer 4 having irregularities on the surface.

2 is a cross-sectional view showing an example in which an optical layered body 1 as a low refractive index layer of the functional layer 6 is further provided on the antiglare layer 4. The low refractive index layer is a refractive index adjusting layer for reducing reflectance by lowering the refractive index of the surface. The low refractive index layer can be formed by applying ionization including a polyester acrylate monomer, an epoxy acrylate monomer, a urethane acrylate monomer, a polyol acrylate monomer, or the like. The coating liquid of the radiation curable material and the polymerization initiator is cured by polymerization. It can be used as a low refractive particle containing LiF, MgF, 3NaF. Low refractive index fine particles of a low refractive material such as AlF or AlF (all having a refractive index of 1.4) or Na ₃ AlF ₆ (cryolite, refractive index of 1.33) are dispersed in the low refractive index layer. Further, as the low refractive index fine particles, particles having voids inside the particles can be suitably used. In the case of particles having voids in the particles, since the portion of the voids can be set to the refractive index of air (≒1), it can be used as a low refractive index particle having a very low refractive index. Specifically, the refractive index can be lowered by using low refractive index cerium oxide particles having voids therein.

The antistatic layer can be formed by applying ionizing radiation including a polyester acrylate monomer, an epoxy acrylate monomer, a urethane acrylate monomer, a polyol acrylate monomer, and the like. The coating liquid of the curable material, the polymerization initiator, and the antistatic agent is hardened by polymerization. As the antistatic agent, for example, metal oxide-based fine particles such as antimony-doped tin oxide (ATO) or tin-doped indium oxide (ITO), a polymer-based conductive composition, a 4-grade ammonium salt, or the like can be used. . The antistatic layer may be disposed on the outermost surface of the optical laminate or between the antiglare layer and the light transmissive substrate.

The antifouling layer is provided on the outermost surface of the optical layered body, and the antifouling property is improved by imparting water repellency and/or oil repellency to the optical layered body. The antifouling layer can be dry coated by a cerium oxide, a fluorine-containing decane compound, a fluoroalkyl decane, a fluoroalkyl decane, a fluorine-containing lanthanoid compound, a perfluoropolyether-containing decane coupling agent, or the like. Or wet coating to form.

At least one of an infrared absorbing layer, an ultraviolet absorbing layer, a color correction layer, or the like may be provided instead of the above-mentioned low refractive index layer, antistatic layer, antifouling layer, or in addition to a low refractive index layer, an antistatic layer, and an antifouling layer. In addition to the layer, at least one of an infrared absorbing layer, an ultraviolet absorbing layer, a color correction layer, and the like may be provided.

Further, in the optical layered body 1 of the present embodiment, it is preferable to form a random agglomerated structure in the antiglare layer 4.

The random agglutination structure refers to a structure in which a first phase containing a relatively large amount of a resin component (a binder component) and a second phase containing a relatively large amount of an inorganic component are three-dimensionally disorderly present, and the second phase system It is unevenly distributed around the fine particles (resin particles). By forming the random agglomerated structure in the antiglare layer 4, fine unevenness can be reduced, and thus the anti-glare property and the blackness at the time of black display can be improved. The random agglutination structure can be formed, for example, by the method described in Japanese Patent No. 5802043.

Further, in the case where a random agglutination structure is formed in the antiglare layer 4, at least one of the above-described low refractive index layer, antistatic layer, antifouling layer, infrared absorbing layer, ultraviolet ray may be provided on the antiglare layer 4. A functional layer 6 such as an absorbing layer or a color correction positive layer.

Further, the optical laminate 1 of the present embodiment can be used to constitute a polarizing plate. Specifically, a polarizing film is formed by adsorbing iodine and a dye on a PVA film, and the optical layered body 1 of the present embodiment is bonded to both surfaces of the polarizing film as a protective film, whereby a polarizing plate can be formed. Alternatively, a polarizing plate can be formed by providing a polarizing layer on the other surface (the surface on which the antiglare layer 4 is not provided) of the transparent substrate 2 of the optical laminate 1 shown in Fig. 1 by a known method. In this case, the optical laminate 1 or other protective film may be further bonded to the polarizing layer. The polarizing layer can be formed, for example, by adsorbing iodine, a dye, and aligning the PVA film.

In addition, the optical layered body 1 of the present embodiment can be used in combination with a liquid crystal panel or the like to constitute a display device. As an example of the configuration of the display device, the optical layered body 1, the polarizing plate, the liquid crystal panel, the polarizing plate, and the backlight unit of the present embodiment are sequentially laminated from the observation side. In addition, the touch sensor can be further laminated to form a display device with a touch sensor.

Further, the optical layered body 1 of the present embodiment can be used as an optical layered body used in a display device such as a smart phone, a tablet computer, or a notebook computer, or a display device (touch panel) with a touch sensor. Examples of the optical layered body include the above-described polarizing plate, antireflection film, and antiglare property, in addition to the optical layer. Specifically, the optical layered body 1 of the present embodiment can be used as a film provided on the outermost surface of a display panel such as a liquid crystal display device, or as a film provided on the outermost surface of the touch panel of the plug-in type or the in-line type. Alternatively, in a touch panel assembled by a direct bonding method or an air gap method, it is used as an intermediate film disposed between the touch sensor and the display panel.

Further, in the present embodiment, an example has been described in which the undercoat layer 3 and the antiglare layer 4 are provided on one surface of the transparent substrate 2. However, the undercoat layer 3 and the antiglare layer may be provided on both surfaces of the transparent substrate 2. 4 optical laminate.

 [Examples]  

Hereinafter, embodiments of the present invention will be described. Further, in the following examples and comparative examples, an optical layered body in which an undercoat layer and an antiglare layer were provided on a transparent substrate was produced. However, the optical layered body of the present invention is not limited to the film having the three layers.

 <Substrate for forming an undercoat layer>  

The following materials were mixed to prepare a composition for forming an undercoat layer.

. Substrate resin

Product Name: UF8001G (no yellowing type oligomeric urethane acrylate), Gongrongshe Chemical Co., Ltd. 0.85 parts by mass

. Polymerization initiator

Product name: Irgacure (registered trademark) 184 (1-hydroxycyclohexyl phenyl ketone), BASF 0.04 parts by mass

. Solvent

 <Composition for forming an anti-glare layer>  

The following materials were mixed to prepare antiglare layer-forming compositions 1 to 4.

 [Solution solution for forming an anti-glare layer 1]  

. Base material resin: UV/EB curable resin LIGHT-ACRYLATE PE-3A (pentaerythritol triacrylate, manufactured by Kyoeisha Chemical Co., Ltd.), refractive index 1.52 91.7 parts by mass

Further, a mixed solvent of toluene and isopropyl alcohol was mixed at a ratio of 16:37 as a solvent.

 [Solution solution for forming an anti-glare layer 2]  

Further, a mixed solvent of toluene and isopropyl alcohol was mixed at a ratio of 16:37 as a solvent.

 [Anti-glare layer forming coating liquid 3]  

Further, toluene was used as a solvent.

 [Applicator 4 for forming an anti-glare layer]  

Further, toluene was used as a solvent.

 <Transparent substrate>  

In Examples 1 to 7, and Comparative Examples 1, 2, and 4, polyethylene terephthalate having a thickness, an in-plane retardation amount (Re), and a thickness direction retardation amount (Rth) shown in Table 1 was used ( PET) as a transparent substrate. Further, in Comparative Example 3, a cellulose triacetate (TAC) film having a thickness shown in Table 1 was used as a transparent substrate.

 <Creation of optical laminate>  

(Examples 1 to 4, Comparative Examples 1, 2, and 4)

On the one surface of the transparent substrate, the coating liquid of the composition for forming an undercoat layer described above was applied by a bar coating method and dried, and then a metal halide lamp was used to irradiate ultraviolet rays with an irradiation dose of 200 mJ/m ² to harden the coating film. Forming an undercoat layer. Moreover, the coating amount of the coating liquid of the composition for forming an undercoat layer was adjusted so that the thickness of the cured film became 40 nm.

Then, the coating liquid of the above-described anti-glare layer-forming composition 1 was applied onto the formed undercoat layer by a bar coating method, and then dried, and then irradiated with ultraviolet rays at an irradiation dose of 200 mJ/m ² using a metal halide lamp. The coating film is cured to form an antiglare layer. In addition, the coating amount of the coating liquid of the composition 1 for the anti-glare layer is adjusted such that the thickness of the cured film becomes a value shown in Table 1.

(Example 5)

An optical layered body was produced in the same manner as in Example 1 except that the antiglare layer-forming composition 2 was used instead of the anti-glare layer-forming coating liquid 1 of Example 1.

(Example 6)

An optical laminate was produced in the same manner as in Example 1 except that the composition 3 for preventing glare layer formation was used instead of the coating liquid 1 for forming an antiglare layer of Example 1.

(Example 7)

An optical layered body was produced in the same manner as in Example 1 except that the antiglare layer-forming composition 4 was used instead of the coating liquid 1 for forming an antiglare layer of Example 1.

(Comparative Example 3)

On the one surface of the transparent substrate, the coating liquid of the above-described antiglare layer-forming composition 1 was applied by a bar coating method and dried, and then a metal halide lamp was used to irradiate a line amount of 200 mJ/ m ^{2 is} irradiated with ultraviolet rays to harden the coating film to form an antiglare layer. Moreover, the coating amount of the coating liquid of the composition for forming an antiglare layer was adjusted so that the thickness of the cured film became the value shown in Table 1.

With respect to the optical laminates obtained in Examples 1 to 7 and Comparative Examples 1 to 4, haze, transmission image sharpness, pencil hardness, degree of rainbow spots, and moisture permeability were evaluated. The evaluation method and evaluation criteria are as follows.

 <Haze>  

The haze was measured by a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7105.

 <Transmission image sharpness>  

The transmission image sharpness was measured in accordance with JIS K7105 using a sharpness measuring device (ICM-1T, manufactured by Suga Tester Co., Ltd.) with an optical comb width of 0.5 mm.

 <pencil hardness>  

The pencil hardness of the surface of the hard coat layer was measured using a pencil scratch tester (HA-301, Tester Industries, Inc.) based on JIS K5600 (4.9 N load). When the measured pencil hardness was 2H or more, it was judged that the surface hardness was sufficient.

 <虹斑>  

The optical laminate of each of the examples and the comparative examples was superposed on the surface of a display (manufactured by Sony Corporation, liquid crystal TV model: KDL-46F5), and the optical laminate was visually observed from the front in a state where the image was displayed on the display. The degree of rainbow spots was evaluated using the following criteria.

◎: No rainbow spots were observed.

○: Although some micro rainbow spots were observed, they were sufficiently suppressed.

△: A rainbow spot was observed.

×: Rainbow spots were clearly observed.

 <Transmoxity (water vapor transmission degree)>  

With respect to the optical layered body of each of the examples and the comparative examples, the water vapor transmission rate in an environment of a temperature of 40 ° C and a relative humidity of 90% RH was measured in accordance with JIS-Z208. The measured water vapor transmission rate was 80 g/m ² . In the case of less than day, it was judged that the water vapor barrier property was sufficient.

The materials and physical properties of the transparent substrate used in the optical laminates of Examples 1 to 7 and Comparative Examples 1 to 4, and the haze, the transmission image sharpness, the pencil hardness, the degree of the rainbow spot, and the moisture permeability were also shown. Evaluation value.

The optical layered bodies of Examples 1 to 7 can sufficiently suppress the rainbow spot to the extent that the visibility of the image is not impaired. Further, it was confirmed that the optical layered systems of Examples 1 to 7 were also excellent in water vapor barrier properties and surface hardness, and excellent in durability.

On the other hand, in the optical layered product of Comparative Example 1, a PET film having a retardation amount of less than 3000 nm in the thickness direction was used as the transparent substrate, and thus the surface hardness of the antiglare layer was lowered.

The in-plane retardation amount of the PET film of the optical layering system of Comparative Example 2 exceeded 600 nm, so that the rainbow spot could not be sufficiently suppressed.

In the optical layering system of Comparative Example 3, cellulose triacetate was used for the transparent substrate, and thus the water vapor barrier property was low.

In the optical layered product of Comparative Example 4, a PET film having a high retardation amount (in-plane retardation amount and thickness retardation amount of about 10000 nm) was used as the transparent substrate. Therefore, although the rainbow spot was suppressed, compared with Examples 1 to 7, The transparent substrate becomes thick. Thus, it was confirmed that the optical layered body of Comparative Example 2 is not suitable for thinning.

According to the present invention, it has been confirmed that, according to the present invention, it is possible to provide an optical layered body which is excellent in durability, is suppressed in rainbow spots, has high visibility, and can be made thinner.

The optical laminate of the present invention can be used as an anti-glare film for suppressing external light reflection, and particularly as a substrate for a polarizing plate or a protective film for a polarizing plate, and can be suitably used for an image display device.

The present invention has been described in detail above, and the foregoing description is merely illustrative of the invention and is not intended to limit the scope. It is self-evident that various modifications and changes can be made without departing from the scope of the invention.

Claims (7)

 An optical layered body in which an undercoat layer is sequentially provided on at least one side of a transparent substrate comprising polyethylene terephthalate having an in-plane retardation of 600 nm or less and a retardation amount in a thickness direction of 3000 nm or more. And an anti-glare layer having a concave-convex shape on the surface.    The optical laminate of claim 1, wherein the optical laminate has a haze of 0.5 to 50%.    The optical laminate of claim 1, wherein the antiglare layer has a pencil hardness of 2H or more.    The optical layered product according to claim 1, wherein the antiglare layer contains one or more layers of an antiglare layer containing a radiation curable resin as a main component.    The optical layered product of claim 1, further comprising at least one of a refractive index adjusting layer, an antistatic layer, and an antifouling layer.    A polarizing plate characterized by laminating a polarizing substrate on the transparent substrate constituting the optical layered body according to any one of claims 1 to 5.    A display device comprising the optical layered body according to any one of claims 1 to 5.